Immunodeficiency Disease

Immunodeficiency disorders predispose individuals to infections due to defects in immune system components, including lymphocytes, granulocytes, monocytes, antibodies, or complement proteins, resulting from genetic abnormalities (primary) or acquired conditions (secondary). The hallmark of these disorders is increased susceptibility to infections characterized by recurrent episodes, severe or prolonged courses, unusual pathogens, or atypical manifestations. B-cell deficiencies primarily lead to recurrent infections with encapsulated bacteria, while T-cell deficiencies are associated with recurrent viral, fungal, or protozoal infections. Phagocytic cell defects result in recurrent bacterial infections due to impaired pathogen engulfment and destruction, and complement deficiencies disrupt the activation of classical, alternative, or lectin pathways, compromising innate and adaptive immune defenses.